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HOW TO: Installing a new LMR 160° Thermostat and Housing
Hello All! Installed a new LMR thermostat today and figured I’d write up a small guide on it.
For those of you that are looking to replace just the factory thermostat with a different one that isn’t the LMR 160° thermostat, the only one that properly works in the OEM housing is the Mishimoto 160° stat. I have extensively tested all the others on the market and they all end up with gasket failures. So, I was on my 6th stat already and figured at this point it’s best to get the best.
First you’ll need to put the car on jack stands and then drain about half of the coolant. To do this, open the petcock valve on the bottom of the driver’s side of the radiator as shown below. Make sure the car is not hot when doing this to ensure you don’t get burned!
The coolant will drain out of this hole so you can put a –clean- drip pan below it to catch it all. We’ll be reusing it later.
Once you get about half of the coolant drained, go ahead and tighten the petcock valve. Next we are going to remove the hose clamps holding the radiator hose and the smaller coolant line onto the outlet housing. On my car I changed these over to regular hose clamps, but likely you will have the kind that require a pair of pliars to release.
Once these are off, remove both hoses carefully. Now we need to remove the three 10MM bolts from the house as shown below:
One these are off, the housing and thermostat assembly can be pulled right out:
Make sure to clean your gasket mating surface. Also note, it is recommended to replace the gasket O-ring when doing this, though I reused mine. This is what the factory thermostat assembly looks like, and you can see the Summit Racing 160° stat that I installed in my car 1100 miles ago. Yep, the gasket is already ripped, and I already modified the spring so it wouldn’t cut into the gasket. Oh well.
For those of you who aren’t installing an LMR, and are just looking to replace the stat with a lower temp one such as the Mishimoto, the next step cover what you’ll need to know. To get the stat out of the housing assembly, you need to push down on the silver area shown below with the red arrows and once the latches clear, twist it. The pic on the right shows it released. If you are doing the LMR stat, you can skip this step.
Ok! Time to install the good stuff! Here is the stat, and the main thing to be mindful of is the “jiggle pin” circled below. The jiggle pin assists in burping the air out of the cooling system when you are filling it back up, and therefore you want it at its highest point, so it needs to face up!
(Personally I prefer to apply some lube to my gasket, such as a very light amount of Vaseline)
Insert the stat into the housing, and position the jiggle pin approximately where I have it on mine so it points up when installed:
Now install it using the previous removal instructions in reverse. Tighten the three 10MM bolts to 89 in. lbs.
To bleed/burp the cooling system, follow this procedure starting from step 4 and going through to step 16:
Please remember that in order to install a lower temp thermostat, your car must have the tune adjusted for it specifically. There are places in the tune for the mechanical thermostat temp as well as the fan turn on temps that need to be adjusted.
Nothing feels better than doing it yourself. I do all my work from specing out to tuning. Will be starting with a custom cam, headwork, headers rockers lifters..etc. Will be my first LT1, still figuring the ins and outs of VVT and direct injection tuning though.
Nothing feels better than doing it yourself. I do all my work from specing out to tuning. Will be starting with a custom cam, headwork, headers rockers lifters..etc. Will be my first LT1, still figuring the ins and outs of VVT and direct injection tuning though.
Agreed! If you run into anything you need help on aside from tuning during your build, let me know!
Thanks! I was going to write one up on wrapping and installing headers but after getting covered in fiberglass I was too pissed to take pics lol
On my c5 with 2 inch headers even with them being coated I did the wrap on them for a few months. But then was talking to the vendor about the wrap. He told me to pull it off that it would get wet & from the heat and water it would pull the coating from the headers.
But for sure with them even coated then doing the wrap it will keep a lot of heat from out from under the hood. I didn't get the c7 headers coated but now that I went with the blower on the car. More than not will be pulling them and doing it on them.
Now back to what you said about the getting covered in the fiberglass I know what you mean that stuff is Even going & getting a show your arms still are mad with it. I don't know how people can work in this stuff all day long. Robert
Nice write up. One thing I might add; when removing the small coolant line going into the thermostat, twist the hose to break it loose. If you try to push and pull the thing before it is loose, there is a chance of breaking the plastic tube. This will render the thermostat and housing unusable (ask me how I know).
I wonder if the Mishimoto is any better than the junk first sold by Summit/Jegs/Lingenfelter?
My 160 T-stat from Lingenfelter's gasket failed, and caused all sorts of misery, putting the car into 'limp' mode and shutting off the AC.
Not sure I want to go down that route again...
Mishimoto stat is built the same as the OEM so it should perform just as well. I like the OEM look and just buying a lower temp stat to replace the higher factory one should be a no brainer while keeping a lot more green in your jeans.
Last edited by C7/Z06 Man; 08-23-2017 at 12:38 AM.
i second this question. Does the car have to be tuned to properly utilize a 160 deg stat?
If you want the car to try to stay at 160, then yes, the tune needs to be updated to turn on the fans earlier.
That being said, you can use the stock tune, but when you are standing in traffic not moving, you will creep up to the 190 normal temp and then higher of course. As soon as you start moving again, it drops down to the stat's temp.
But then again, I have a Dewitt's Radiator and I got a LOT of extra cooling capacity over stock so I am not sure how it would behave on a stock radiator.
One thing I will chime in with. Another forum member mentioned how he pressed out the bulb on a Mishimoto and one could replace it with a 170 or 180. I was running the 180 Summit stat (no issues) but I figured I was on borrowed time. So I bought a Mishimoto and used a vice and a couple small blocks of wood and the bulb pressed out easily on the Mishimoto. I took a bulb out of another 170 stat I had laying around but it did not press in tight to the Mishimoto so I had to play with it a little and got it to lock in tight. Been running it for quite a while now and I like 170. Car seems to run good. No issues noted so far.
Definitely the Mishimoto gasket looks like OEM so I don't think it will get torn by the spring like the Summit stat could.
If I could do it then anyone could replace the bulb.
I am so glad I found this thread as I am about to install a 160* thermostat and tune this week! Did you guys re-use the coolant you drain out or add new dexcool/water mix?
I am so glad I found this thread as I am about to install a 160* thermostat and tune this week! Did you guys re-use the coolant you drain out or add new dexcool/water mix?
I changed out but I did that because I changed the mixture. You should be able to reuse it though.
Thanks for the details. The picture of the petcock was quite hard to get my bearings straight. Took me a while to find it. Realized it was because my Procharger intercooler tubing was blocking view to it.
Future reference to Procharger and other aftermarket guys. Take off the undertray infront of the radiator to access the petcock.
After that, it was simple.
i installed a summitt 170 tstat by using the stock tstat disk and pressing out the bulb like MyghtyM0use suggested (just lay the tstat on a large socket and tap it with a mallet or if you have a vise thats a much better method). The summit tstat has a smaller diameter so you need to use needlenose pliers to work the disk edges in a little. Press or tap back into position.
I didn't tune the fan. Tested. Car heats up to 172-274 Coolant / oil on the highway. In stop and go it rises to 194 until the fan comes on but then 5 minutes of driving and it's below 180 again.
Per stock LT1 ect spark tables you gain 1° of timing below 176 coolant temp and lose 1° above 194. I have not datalogged to check this.
Last edited by BrunoTheMellow; 03-24-2019 at 04:46 PM.
08-12-2017, 08:53 PM
HOW TO: Installing a new LMR 160° Thermostat and Housing
On my c5 with 2 inch headers even with them being coated I did the wrap on them for a few months. But then was talking to the vendor about the wrap. He told me to pull it off that it would get wet & from the heat and water it would pull the coating from the headers. 
